From: Isabella Ghiurea <isabella.ghiurea@nrc-cnrc.gc.ca>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: pgsql-admin@postgresql.org <pgsql-admin@postgresql.org>
Subject: Re: WAL log shipping + Streaming replication PG 9.0 questions
Date: Tue, 19 Oct 2010 07:46:48 -0700
Message-ID: <4CBDAF58.9050503@nrc-cnrc.gc.ca> (raw)
In-Reply-To: <AANLkTi=DHscwip3JhGOSPBA9H_VcqHHFjdJy5Bomj2Tv@mail.gmail.com>
References: <4CBC8886.9040608@nrc-cnrc.gc.ca>
<AANLkTi=DHscwip3JhGOSPBA9H_VcqHHFjdJy5Bomj2Tv@mail.gmail.com>
Fujii Masao wrote:
> On Tue, Oct 19, 2010 at 2:48 AM, Isabella Ghiurea
> <isabella.ghiurea@nrc-cnrc.gc.ca> wrote:
>
>> I have some questions regarding hot standby + streaming replication (PG
>> 9.0) : what is master/primary server behavior if archive_command fails
>> due to archive directory off line/unavailable?
>>
>
> Unarchived WAL files continue to accumulate in pg_xlog directory while
> the archive directory is unavailable. Then, if pg_xlog directory is
> filled up, the PostgreSQL server causes the PANIC error.
>
>
>> How about standby server behavior if restore command fails due to
>> archive_master directory not available?
>>
>
> After restore_command fails, the standby tries to read WAL file from
> its pg_xlog directory. And, if there is no WAL file to recover in pg_xlog,
> the standby tries to connect to the master and read the streamed WAL files
> from the master.
>
> Regards,
>
>
Thank you for all details.
For the last question I ' m still a bit confused: if master_archive off
line ( no archived WAL's available) what will be state of standby server ?
Basically we are trying to design a solution where WAL archived
directory is not a "single point of failure" for whole system ( we are
planing to have WAL archived master directory on a separate machine and
both server primary and standby will have read/write here) if this
servers fails , we want to be able to continue normal user operation
on master while standby server will have some latency.
Isabella
--
-----------------------------------------------------------
Isabella A. Ghiurea
Isabella.Ghiurea@nrc-cnrc.gc.ca
Canadian Astronomy Data Centre |http://www.nrc-cnrc.gc.ca/eng/services/hia/data-centre.html
National Research Council of Canada, Herzberg Institute of Astrophysics
5071 West Saanich Road, Victoria BC V9E 2E7, Canada
Phone: 250 363-3446 fax: 250 363-0045
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To: pgsql-admin@postgresql.org
Cc: isabella.ghiurea@nrc-cnrc.gc.ca, masao.fujii@gmail.com
Subject: Re: WAL log shipping + Streaming replication PG 9.0 questions
In-Reply-To: <4CBDAF58.9050503@nrc-cnrc.gc.ca>
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